(Recasts making clear that only the woman has been released, other details)

SANAA, Jan 10 (Reuters) - Militants linked to al Qaeda have freed a South African woman kidnapped in the Yemeni city of Taiz in May and mediators are trying to secure the release of her husband, a Yemeni security official and South African negotiators said on Friday.

Accounts of the case were confused, after local officials and tribal sources said earlier in the day that both Pierre and Yolande Korkie had been released. Later they said only the woman had been set free.

Both were in good health, the sources told Reuters.

The Yemeni security source said Yolande had been released after tribal mediation efforts and her husband was expected to be freed "within days". They have been held in a mountain area under the control of militants in the southern Abyan province, the source said.

The couple had been working as teachers in Yemen for the previous four years, according to Imtiaz Sooliman, head of South Africa Gift of the Givers, a non-governmental organisation which has been negotiating for their release.

"Only Yolande has been released. We need to renegotiate for Pierre, they've given us eight days and want $3 million," Sooliman told Reuters.

He said no ransom had been paid for the woman after the kidnappers were told the South African government would not pay and the family could not afford one, he said, adding the kidnappers had initially thought the couple were American.

In a statement, the South African government welcomed the release of Korkie and said her husband "is still being held captive".

Kidnapping of foreigners in Yemen is common, often carried out by disgruntled tribesmen seeking to press the government to free jailed relatives or to improve public services, or by Islamist militants linked to al Qaeda.

Yemen has been grappling with an Islamist insurgency which took advantage of unrest in 2011 inspired by the Arab Spring to seize control of some southern cities.

The insurgents were beaten back by government forces but have since regrouped and mounted attacks on government officials and installations.

Lawlessness in the poor Arabian Peninsula state has alarmed neighbouring Saudi Arabia, the world's leading oil exporter, as well as the United States, which increasingly views Yemen as a front line in its struggle against al Qaeda. (Reporting by Mohammed Ghobari in Sanaa and Xola Potelwa in Johannesburg; Writing by Rania El Gamal in Dubai; Editing by Andrew Roche)

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